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Fatal Southwest Accident Puts Focus on Widely Used Engine

Failure of CFM engine is set to spur more scrutiny across fleets around the globe

National Transportation Safety Board investigators examine damage to the engine of the Southwest Airlines plane that made an emergency landing at Philadelphia International Airport on Tuesday.
Photo:
NTSB/Associated Press

CFM International—a joint venture between General Electric Co. and France’s
Safran SA
SAF -0.37%
—makes engines that have become a mainstay of commercial aviation. The engines power most of
Boeing Co.
BA 3.77%
and Airbus SE’s single-aisle planes, the workhorses of the industry.

On Tuesday, one of two CFM56-7B engines ruptured on a Boeing 737-700 operated by Southwest. The engine broke apart while the plane was at cruising altitude, flying from New York’s LaGuardia Airport to Dallas Love Field, with 149 passengers and crew aboard. Metal pieces struck the fuselage, though the details of what happened inside the cabin are still unclear.

Southwest two years ago suffered a similar failure on another CFM56 engine, forcing the plane to land but not resulting in injuries.

A probe of that incident showed evidence of fatigue cracks in some of the blades. In response, the Federal Aviation Administration last year proposed enhanced inspections of certain CFM engines. It hasn’t yet made the safety fix mandatory. The National Transportation Safety Board said it would examine whether there were any common factors connecting the two CFM56 incidents at Southwest.

The airline, meanwhile, said late Tuesday it was stepping up inspections of the CFM56s used in its fleet. CFM International said it was sending a team of experts to aid the NTSB probe.
Korean Air
on Wednesday said it would inspect the fan blades on its 737s in response to the incident.

The widespread use of the engine and its unusually dramatic failure are likely to spur more scrutiny across fleets around the globe. European air-safety regulators said Wednesday they were “assessing the situation” and working with U.S. counterparts.

On average, a CFM56-powered plane takes off somewhere in the world every two seconds. The CFM56-7B version involved in Tuesday’s incident has been in service since 1997 and is used in more than 6,700 airliners.

Engine failures are rare but aren’t unheard of. Robert Sumwalt, chairman of the NTSB, said investigators see about three to four incidents each year.

A different engine that powered an Airbus A380 superjumbo operated by
Air France
failed on a flight from Paris to Los Angeles in September. The plane diverted to Goose Bay, Canada. The accident investigation hasn’t been completed.

A Southwest Airlines passenger broadcast a video on Facebook Live midair after an engine broke apart, apparently rupturing a window and killing a passenger.

Engines are the often-overlooked lifeblood of the aviation industry. Engine makers spend billions of dollars to eke out small-percentage improvements in fuel efficiency to woo airliner buyers.

Airlines and plane makers have endured a recent run of operational headaches because of problems with these mini power plants. British aircraft-engine maker
Rolls-Royce Holdings
PLC last week warned that some of its engines powering Boeing 787 Dreamliner long-haul planes would require more frequent inspections because components were wearing out faster than expected. U.S. regulators, as a precaution, have required airlines that use those engines to chart courses that bring planes closer to airfields to which they could divert.

Airlines that uses those engines have had to ground planes and cancel flights because of an earlier round of checks on them. Rolls-Royce, no longer affiliated with the luxury-car maker, has said it could take until at least 2021 to fix all the engines.

Pratt & Whitney, a unit of
United Technologies Corp.
, has struggled with the development and production of its new geared turbofan engine. The engine maker halted shipments to Airbus for three weeks in February as it worked to fix the design of components, which had been wearing out too soon. Airlines have had to idle planes in response to actions taken by European air-safety regulators. Pratt has said it is working to fix the problem.

CFM also is struggling with its newest engine, the Leap used on Boeing’s new 737 Max narrow-body and some Airbus A320 models. GE Aviation President David Joyce last month said the company was about six weeks late on engine deliveries to Boeing and Airbus.

—Eun-Young Jeong contributed to this article.

Corrections & Amplifications The engine on an American Airlines Boeing 767 blew up on takeoff in 2016 because of a manufacturing anomaly of a component. A previous version incorrectly gave the probable cause of the failure. (April 18)